"We've had a number of those in the recent past."

Canadian Press

Associated Press

In this May 1, 2014, file photo, a man who suffered severe burns to 12 percent of his body when butane fumes ignited while he was making hash oil at home, demonstrates how he made the marijuana concentrate.

CALGARY — Alberta law enforcement officials say they are worried that the legalization of marijuana could lead to potentially explosive consequences for users taking a do-it-yourself approach to making cannabis derivatives at home.

Just over a month ago, Canadians were given the right to purchase dried and fresh cannabis and unconcentrated forms of cannabis oil.

It is likely to be another year before concentrates will be legalized.

"What's going to happen — and this is just my prediction — is that people are going to do a butane hash extraction at home and they're going to blow themselves up," said Sgt. Guy Pilon, clandestine lab co-ordinator with the Edmonton Police Service.

"We've had a number of those in the recent past. People blow themselves up trying to make this weed oil."

Pilon said before cannabis was legalized, Edmonton police dealt with six butane hash oil labs. He expects many Canadians might want to experiment and attempt to make their own with the pot that they can now purchase at a store.

"It's butane honey oil, so it's not hash. It's a weed oil. It's a golden- coloured syrup and from that they can take it and create shatter which is a really potent concentrate."

Sometimes described as the "crack of marijuana," shatter is a hash oil concentrate made by using butane to extract resin with high concentrations of THC from a marijuana plant. The name refers to the end product which looks like a sheet of toffee.

Instructions can be found online

A small amount of the drug is dabbed on a heated surface and inhaled or smoked in a pipe.

Because butane is used, a simple spark can create an explosion.

"With the regulation of cannabis and the decriminalization of it, one aspect that we need to focus on is public education," said Calgary police Insp. Kevin Forsen with the community support section.

"People can go onto the internet and read how to do it. Nobody's going to post how dangerous it is or very few people are going to do it."

Forsen points out that people messing around with butane at home put not only themselves at risk but others living nearby.

"Those are extremely dangerous processes and there is that risk," he said.

"When you look at shatter, the amount of THC that's in it can run up to between 90 and 95 per cent, so it's very highly concentrated and that might be something the illicit market would want to capitalize on right now."

People can go onto the internet and read how to do it. Nobody's going to post how dangerous it is or very few people are going to do it.Insp. Kevin Forsen

Alberta's justice minister hadn't heard about police concerns, but said they appear legitimate and she is willing to discuss the possibility of more education.

Kathleen Ganley said the government has a plan in place but knew there would be bumps along the road once cannabis became legal.

"There was always an expectation that was going to have to fluctuate somewhat to deal with unforeseen circumstances," she said.

"This is the first time since Prohibition on alcohol was lifted that we've dealt with something that's a legalization of this scale, so I expect that we will have to respond to those issues."